Nasopharyngeal sheath for nasogastric intubation

ABSTRACT

This invention discloses a system for safe and non-traumatic insertion of a nasogastric tube, said system comprises of a nasogastric tube and a curved rubber nasopharyngeal sheath, long enough to reach the hypopharynx from the nostrils. Said sheath has two longitudinal tear-off lines over its full length and two ringed handles to apply lateral pull traction. The diameter of both the tube and the sheath are such that the sheath can accommodate the nasogastric tube. This system can also be used in patients who are endotracheally intubated.

CROSS-REFEFERNCE TO RELATED APPLICATION

Not Applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention is in the field of medicine, particularly in relation to nasogastric catheter placement.

2. Description of the Prior Art

Nasogastric intubation has been practiced for a very long time. This has been always a difficult and uncomfortable procedure. The tip of the nasogastric tube frequently causes injury to the nasal passage mucosa. This is because of the anatomical configuration of human nasal passage which includes a sharp curve at the nasopharynx. There are various types of nasogastric tubes from simple ones to the recently introduced sump drain nasogastric tubes. A problem that is always present with these tubes is their rigidity vs. maneuverability. If the catheter is rigid enough to be able to be maneuvered and pushed through the nasopharynx and hypopharynx into the esophagus, it may well injure the mucosa by it's tip, and if it is made of very soft material it may not be easily maneuvered and needs a rigid stylet to assist during insertion, but these will collapse their internal lumen if connected to suction because their wall is so soft and pliable and are suitable only for purpose of feeding not for suctioning. Examples of the first type of tubes are the currently used nasogastric suction catheters and examples of the second group include the current enteric feeding tubes.

In order to overcome these shortcomings, several inventions have been disclosed before.

For the rigid catheters a lumen seeking nasogastric tube with a flexible tip was disclosed by Klingenstein (U.S. Pat. No. 5,700,252, December, 1997). Another prior art is a stylet to help the tube negotiating the nasopharyngeal curve (Micek, U.S. Pat. No. 4,747,827, May, 1988).

For the softer tubes disclosures includes multiple type of conduit tubes to push the feeding tube through the nasopharynx or hypopharynx all the way to the stomach and then removing the conduit (Okada, U.S. Pat. No. 4,887,997, December 1989) or stylets to temporarily stiffen the tube (Etheredge, U.S. Pat. No. 4,938,746, March 1988; Beal, U.S. Pat. No. 4,257,421, March 1981). The conduit proposed by Okada proposed a conduit that it is to be inserted all the way to the stomach and then after placement of the nasogastric tube that conduit is removed via a special separator. This is different to the current disclosed nasopharyngeal sheath because the main difficulty and concern for mucosal injury still exists with the Okada's conduit. It is mainly targeted for placing the very soft feeding tubes, which are not suitable for nasogastric suctioning. Kwak (U.S. Pat. No. 4,175,564) proposes to insert the nasogastric tube through the nose and Dull it through the mouth then a guide to be inserted through the mouth into the esophagus and the nasogastric tube will pass through it into the esophagus. This technique still requires passing the nasogastric tube through the nasopharyngeal airway with potential for causing injury. There are also innovative approaches including swallowing an absorbable string to guide the catheter during insertion (Peters, U.S. Pat. No. 201,556, February 1994).

The shape of human nasopharynx is such that it has a sharp curve at its passage to pharynx and subsequently hypopharynx. Passing tubes and catheters often causes injury to the mucosa and bleeding of the posterior wall of the nasopharynx. Tubes that have inherent curve on the other hand can easily pass through this curve; examples are the current nasopharyngeal airway catheters. The same problem exits even when a patient is endotracheally intubated. Placing a nasogastric tube can still be very traumatic. Also, in patients who have problems with their coagulation, conventional nasopharyngeal intubation can potentially cause significant bleeding because of the mucosal injury.

It is to be said that the disclosed nasopharyngeal sheath is different comparing to the current commercially simple nasopharyngeal airway catheters or their various modifications like the ones described by Downing or Linder among others (U.S. Pat. No. 4,821,715 which issued on Apr. 18, 1989 to Michael V. Downing, U.S. Pat. No. 5,664,567 which issued on Sep. 9, 1997 to Gerald S. Linder and in U.S. Pat. No. 5,692,506 which issued on Dec. 2, 1997 also to Gerald S. Linder). The scopes of function of the two are completely different. The curve of the nasopharyngeal airway catheter is such that it places the tip of the catheter as close to the tracheal opening as possible and all the modifications mentioned above aim to better deliver oxygen to the patient, while the disclosed sheath has a wider curve to be able to point more posteriorly towards the esophagus rather than the trachea which is located more anteriorly. Also none of the current nasopharyngeal airways have the tear-off mechanism or the pulling rings.

The disclosed invention uses a curved rubber tube to secure a safe pathway for the nasogastric tube into the hypopharynx. Once there, the tip of the rubber sheath positions the nasogastric tube tip above the esophageal aperture, therefore the catheter can be easily pushed into the esophagus. For further understanding and appreciation of the invention and its advantages reference is made to the Drawings and Detailed Description below.

BRIEF SUMMARY OF THE INVENTION

This invention provides a comfortable and safe way to insert any nasogastric tube. According to the present invention a curved rubber sheath is first inserted into the nasopharynx all the way to the hypopharynx. The natural curve of this tube corresponds to the natural curve of these areas in human body. The beveled and round edge as well as its rubber material all minimizes the risk of mucosal injury. By bending the patient's head forward the curved sheath tip will position itself right above the esophageal opening. Then through this sheath a nasogastric catheter can easily slide into the esophagus with no trauma to the mucosa, and then the sheath is retracted outside and torn apart. As the last step the nasogastric catheter will be fixed to the nose.

The objective of this invention is to provide a safe and less traumatic method and means for introducing nasogastric catheters.

Another objective of this invention is to improve the success rate of esophageal intubation vs. accidental tracheal intubation.

Another objective of this invention is to prevent injury and bleeding in patients especially those with coagulation problems.

Yet another objective of this invention is to provide a less traumatic nasogastric intubation technique for patients who are under general anesthesia and have endotracheal intubation and need to have a nasogastric tube as well.

Through these two goals the ultimate objective of this invention is to improve patient's comfort and tolerance during a difficult procedure.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIGS. 1 and 2 are views of the human aero-digestive tract and the usual path of a nasopharyngeal tube.

FIGS. 3, 4 and 5 are the nasopharyngeal sheath from different views.

FIGS. 6, 7 and 8 illustrate the technique of nasogastric intubation using the nasopharyngeal sheath.

DETAILED DESCRIPTION OF THE INVENTION

The anatomy of human nasopharynx and oropharynx is shown in FIGS. 1 and 2. The bold line (11) indicates the path of a nasogastric tube. As it is demonstrated a straight tube placed in the nose will hit the posterior nasopharyngeal wall (12) before it is pushed down towards the oropharynx. After entering the esophagus the path of a nasogastric tube to the stomach is almost a straight line (13). The conventional nasogastric intubation technique involves negotiating the curve of the nasopharynx. The injury usually occurs in the nasal mucosa or more severely at the nasopharynx.

Referring to FIGS. 3, 4 and 5, the nasopharyngeal sheath has a curve to correspond to the natural curve of human upper aero-digestive tract. It is made of medically approved rubber or latex. This material is flexible enough to cause minimal damage to the surrounding mucosa. Also by using the ordinary medical lubricators the nasogastric tube can slide through them with minimal friction. Its tip (21) is rounded and beveled to facilitate its passage through the nasal mucosa. There are two tear-off lines that extend through the entire length of the catheter at 12 and 6 o'clock. These are slits in the body the nasopharyngeal sheath that extend from its external surface to just short of its internal lumen. Once the rings are pulled apart the sheath will rip through the two lines. There are two rings (22) at its end to facilitate it's tearing through the tear-off lines (23) at the end of the procedure. The rings are attached at 3 and 6 o'clock position and are large enough to be easily grabbed and pulled apart. The nasogastric tube has marking (25) on its body to indicate when the tip of the tube is at the distal end of the nasopharyngeal sheath. It is to be mentioned that although it will be very convenient to have such a marking on the nasogastric tube, in alternative embodiments the sheath could be used with any nasogastric tube even without the marking as long as the inner lumen of the nasopharyngeal sheath can accommodate that nasogastric tube.

The sheath has a thick wall about 1-2 millimeters (24), so that although flexible, but its lumen does not completely collapse during passage through the nasal airway. The length of the sheath should be long enough to extend from the nares to the hypopharynx. It should be supplied in different lengths for different patient populations. The internal lumen also may vary. The usual size of nasogastric tubes is from 8 French to 18 French. Therefore the in internal lumen of the nasopharyngeal sheath should be manufactured in different sizes to be able to accommodate the corresponding nasogastric tube while avoiding an unnecessary large sheath to reduce patients' discomfort. One easy solution would be to supply the nasopharyngeal sheath and the corresponding nasogastric tube in one kit.

The technique of placement is depicted in FIGS. 6, 7 and 8. This includes placing the lubricated nasopharyngeal sheath initially (31) through the nose all the way to the hypopharynx. The curve of the tube will make this part more tolerable and less traumatic, and then the lubricated nasogastric tube is placed through the sheath. The nasogastric tube is passed through the sheath all the way to the marking (32). This protects the mucosa from injury or irritation and reduces patient's discomfort. The mark corresponds to the point the nasogastric tube tip (33) is right at the proximal end of the sheath as is depicted in FIG. 7.

The patient is instructed to swallow a few sips of water, this further causes the glottis to close the tracheal opening and stimulates the pharyngeal muscle contractions, and then the nasogastric tube can easily be passed into the esophagus and subsequently from there to the stomach is almost a straight route. This is demonstrated in FIG. 8. Bending the head also helps to bring the beveled end of the tube with the posterior pharyngeal wall and places the tip of the nasogastric tube above the esophageal aperture.

Once the nasogastric tube is in final position, the nasopharyngeal sheath is pulled back out of patient's body and is torn apart through the tear-off lines as it is depicted in FIG. 9. The nasogastric tube is then fixed to the patient's nose. It should be mentioned that in patients who are endotracheally intubated moving the head or swallowing water cannot happen, yet the curve of the nasopharyngeal sheath will facilitate the nasogastric tube placement. Also although in these drawings the nasogastric tube has been illustrated as a simple tubular structure, the current invention can also use the more recently introduced sump suction catheters or the feeding tubes. It is also to be noted that the nasopharyngeal sheath as well as the nasogastric catheter can be manufactured in different matching diameters and lengths so that they can be used a wide range of patient population. 

1. A nasogastric intubation assembly comprising of a curved nasopharyngeal sheath and a nasogastric catheter having proximal and distal ends, sufficiently long to reach the desired internal point from patient's nostril.
 2. The assembly of claim 1, wherein the nasopharyngeal sheath has a cylindrical wall with proximal and distal ends, said distal end arranged to be inserted into a nasal passage of a patient and positioned in the hypopharynx above the esophageal aperture and said proximal end arranged to be positioned externally of the patient at the patient's nares, said tube having an open central passageway from said proximal end to said distal end;
 3. The assembly of claim 2, wherein the said nasopharyngeal sheath is curved appropriately to pass through the nasopharynx and is made of soft rubber so that it is less traumatic to the body. The said sheath has a thick wall so the lumen formed in its wall will not readily collapse.
 4. The assembly of claim 2, wherein the said nasopharyngeal tube has an internal bore slidably receiving and encasing the nasogastric tube.
 5. The assembly of claim 3, wherein the distal end of the sheath is beveled with rounded edges to facilitate it maneuverability in the nasopharynx and make it less traumatic when passing through the nasal airway.
 6. The assembly of claim 4, where in there are two longitudinal tear-off lines on the superior and inferior parts of the sheath to facilitate it's tearing at the end of the insertion procedure.
 7. The assembly of claim 5, wherein there are two rings attached to the proximal end of the sheath on both lateral parts to serve as handles to apply lateral pull in order to tear off the sheath.
 8. The assembly in claim 1, wherein the distal end of the nasogastric tube is blunt with lateral holes to be less traumatic while passing the tube through the esophagus.
 9. The nasogastric tube in claim 8, wherein there is a mark on the tube which is located at equidistance from the distal end of the tube as the length of the said nasopharyngeal sheath, so that when the nasogastric tube is placed inside the sheath and advanced just to the distal tip of the sheath the mark is at the proximal end of the sheath.
 10. A method for inserting the nasogastric tube, comprising of inserting the lubricated distal beveled end of the said nasopharyngeal sheath into patients nostril along its curve. The said sheath is advanced so that the said two rings are in contact with patient's nose and this prevents the said sheath to advance more. The said nasogastric tube is lubricated and is inserted into the said nasopharyngeal sheath. The nasogastric tube is advanced through the sheath; this protects the nasal airway as well as nasopharynx from injury by the tip of the said nasogastric tube trying to pass through the curves of the nasopharynx. The advancement is continued until the said marking on the nasogastric tube is at the proximal end of the nasopharyngeal sheath. This marks the point where the tip of the nasogastric tube is at the distal end of the said nasopharyngeal sheath. Patient's head is bent forward; this as well as the natural curve of the said sheath will position the distal end of the said sheath in contact with posterior wall of the hypopharynx just above the esophageal aperture. Patient is instructed to drink a few sips of water. This closes the glottis and opens the upper esophageal sphincter system. Since the tip of the introducing sheath is positioned just above the esophageal opening the nasogastric tube can easily be passed in the esophagus and from there to the stomach it is almost a straight route. After complete insertion of the nasogastric tube to the desired point internally, while holding the nasogastric tube in place at the nostril, the nasopharyngeal sheath is pulled back out of patient's body and is grabbed from the two said rings and torn apart along the said tear-off lines. The nasogastric tube is subsequently fixed to patient's nostril using tape or other commercially available fixtures. In patients who are endotracheally intubated the same technique will be done without bending their head or swallowing water.
 11. A nasopharyngeal sheath to reduce the trauma and discomfort during insertion of a nasogastric tube comprising of: a. A curved tube, sufficiently long enough to reach to hypopharynx from nose. b. Means for retrieval of said curved tube after placement of a nasogastric tube comprising of two tear-off lines and two handles
 12. The sheath in claim 11, wherein said tube has a cylindrical wall and a central passageway with a tip and an end.
 13. The sheath in claim 11, wherein said tube is curved appropriately to be compatible with curve of the human nasopharyngeal airway and is made of soft, elastic material so that it is less traumatic to the body.
 14. The sheath in claim 11, wherein said tube has a sufficiently thick wall so it will not readily collapse during insertion.
 15. The sheath in claim 11, wherein said tube has a tip that is beveled with rounded edges to facilitate maneuverability in nasopharynx and make it less traumatic when passing through nasal airway.
 16. The sheath in claim 11, wherein the said longitudinal tear-off lines are two slits located on top and bottom and over the entire length of said curved tube extending from the outer wall to just short of the inner wall of said curved tube so that by application of lateral pull through said handles, said curved tube tears apart through said two longitudinal slits.
 17. The sheath in claim 11, wherein said two handles are two rings attached to the left and right of said end of said curved tube.
 18. A method for inserting a nasogastric tube to minimize the chance of trauma to a patient, comprising of: a. Lubrication and Insertion of a curved tube with a beveled and rounded tip into a patient's nostril. Said tube is advanced towards hypopharynx so said tip reaches hypopharynx above esophageal opening. Said tube has two rings at its end that prevent it from advancing further. b. A nasogastric tube is lubricated and inserted into said curved tube and advanced until the tip of said nasogastric tube is at said tip of said curved tube. c. Patient's head is bend forward if clinically feasible and said nasogastric tube is further inserted forward into esophagus and then to the desired internal point. d. Said nasogastric tube is held in place at nostril and said curved tube is pulled back out of patient's body and is grabbed from said two rings and torn apart along two tear-off lines over the body of said curved tube. e. Said nasogastric tube is subsequently fixed to patient's nose.
 19. The method in claim 18, wherein said nasogastric tube has an external diameter less than the inner diameter of said curved tube and can slide through said curved tube.
 20. The method in claim 18, wherein said nasogastric tube has a mark that is located at equidistance from its tip as the length of said curved tube. 